Circuit and apparatus for verifying a chamber seal, and method of depositing a material onto a substrate using the same

Abstract

An improved door closure indicator is provided. The indicator operates on pressure levels read within a pressurized chamber rather than from proximity switches coupled between the chamber and the door. If the door seals to the chamber, pressure within the chamber will quickly change, and the change will be read on a pressure sensor indicative of the door closure. According to one example, the chamber can comprise a vacuum chamber and the pressure sensor can be a vacuum monitor. Once vacuum is detected, it is determined with more absolutism that the door is actually closed rather than having to rely upon switch operation and/or alignment of the door activation mechanism to proximity switches arranged on the chamber housing. The processing tool which embodies the chamber includes a chamber controller which incorporates various switches and relays which channel pressure readings taken from the chamber to a load controller, and also delays pressure readings after opening a half-gate valve operably coupled between a vacuum pump and the chamber.

What is claimed is: 
     
       1. An apparatus for determining closure of a door, comprising: a chamber having first and second apertures extending into the chamber;   a pressure delivery unit coupled to the first aperture; and   a pressure monitor coupled in gaseous communication with the pressure delivery unit and configured to generate a signal indicating sealed closure of said door over the second aperture when a pressure reading within the pressure monitor varies from a pre-defined amount.   
     
     
       2. The apparatus as recited in claim 1, wherein said pressure delivery unit comprises a vacuum pump and said pressure monitor comprises a vacuum monitor. 
     
     
       3. The apparatus as recited in claim 1, further comprising a tube sealed about the first aperture and extending between the pressure delivery unit and the chamber. 
     
     
       4. The apparatus as recited in claim 3, wherein said pressure monitor is mounted through a sidewall of said tube. 
     
     
       5. The apparatus as recited in claim 1, wherein said door comprises a gas impermeable membrane extending about a surface of the door between the door and an outer surface of the chamber which surrounds the second aperture. 
     
     
       6. The apparatus as recited in claim 5, wherein said membrane is substantially impervious to gas flow during a time when the door is compressed against the surface of the chamber surrounding the second aperture. 
     
     
       7. The apparatus as recited in claim 1, wherein said door is coupled to a carrier adapted to receive semiconductor wafers such that the semiconductor wafers extend into and are pressure sealed within the chamber during times when the door is closed over the second opening. 
     
     
       8. The apparatus as recited in claim 1, wherein said pressure monitor is configured to generate a signal indicating sealed closure of said door over the second aperture when a pressure reading within the pressure monitor varies by a pressure differential amount from a pre-defined amount equal to an ambient pressure level outside out of the chamber, and further wherein the pressure differential amount is between 10 and 500 torr. 
     
     
       9. A method for verifying closure of a vacuum sealed door across an aperture extending into a semiconductor fabrication chamber, comprising: driving the door into a position across the aperture;   applying a first vacuum to the chamber; and   verifying sealed closure of the door across the aperture if a pressure monitor coupled in gaseous communication with a pressure delivery unit coupled to a first aperture of the chamber reads a pressure that varies from a pre-defined amount and thereafter generates a signal indicating sealed closure of the door over the aperture.   
     
     
       10. The method as recited in claim 9, wherein said applying comprises drawing vacuum gas and particulate matter from the chamber through a secondary conduit of relatively small diameter compared to the diameter of a main conduit. 
     
     
       11. The method as recited in claim 10, further comprising applying a second vacuum amount greater than the first vacuum amount subsequent to verifying seal of the door. 
     
     
       12. The method as recited in claim 11, wherein said applying the second vacuum comprises drawing gas and particulate matter from the chamber through the main conduit to draw pressure within the chamber further below atmospheric pressure. 
     
     
       13. The method as recited in claim 12, wherein said main conduit draws pressure within the chamber less than 300 millitorr. 
     
     
       14. The apparatus as recited in claim 4, wherein the tube is a main conduit, and further comprising a secondary conduit having a smaller diameter than the main conduit, the secondary conduit extending between the pressure delivery unit and the main conduit, and wherein the secondary conduit is configured to allow pressure delivery therethrough from the pressure delivery unit to the chamber. 
     
     
       15. The apparatus as recited in claim 8, wherein the pressure differential amount is between 20 and 300 torr. 
     
     
       16. The apparatus as recited in claim 15, wherein the pressure differential amount is between 40 and 100 torr. 
     
     
       17. The method as recited in claim 9, wherein said verifying sealed closure of the door across the aperture further comprises verifying sealed closure of the door across the aperture if a value of the first vacuum varies by a pressure differential amount beyond a pre-determined pressure equal to an ambient pressure level outside out of the chamber, and wherein the pressure differential amount is between 10 and 500 torr. 
     
     
       18. The method as recited in claim 17, wherein the pressure differential amount is between 20 and 300 torr. 
     
     
       19. The method as recited in claim 18, wherein the pressure differential amount is between 40 and 100 torr.